Cristina Prandi | Università degli Studi di Torino (original) (raw)
Papers by Cristina Prandi
Current Genetics, 2016
Strigolactones (SLs) as components of root exudates induce hyphal branching of arbuscular mycorrh... more Strigolactones (SLs) as components of root exudates induce hyphal branching of arbuscular mycorrhizal (AM) fungi which is thought to favor the establishment of the beneficial symbiosis. Little is known on how AM fungi respond to SLs. Since AM fungi are poor model systems due to their obligate biotrophism and the lack of genetic transformation protocols, we took advantage of the sensitivity of several phytopathogenic fungi to GR24, a synthetic SLs analog. With the aim to identify the molecular determinants involved in SLs response in AM fungi and assuming conserved mechanisms in the fungal kingdom, we exploited the fungal pathogens Botrytis cinerea and Cryphonectria parasitica, for which mutant collections are available. Exposure of B. cinerea and C. parasitica to GR24 embedded in solid medium led to reduction of fungal radial growth. We set up the screening of a set of well characterized gene deletion mutants to isolate genotypes with altered responses to SLs. Two B. cinerea mutants (defective of BcTrr1, a thioredoxin reductase and BcLTF1, a GATA transcription factor) turned out to be less responsive to GR24. One feature shared by the two mutants is the overproduction of reactive oxygen species (ROS). Indeed, an oxidizing effect was observed in a B. cinerea strain expressing a redox-sensitive GFP2 in the mitochondrial intermembrane space upon exposure to GR24. ROS and mitochondria are therefore emerging as mediators of SLs actions.
Molecules
During the last decade, a wide spectrum of applications and advantages in the use of deep eutecti... more During the last decade, a wide spectrum of applications and advantages in the use of deep eutectic solvents for promoting organic reactions has been well established among the scientific community. Among these synthetic methodologies, in recent years, various examples of biocatalyzed processes have been reported, making use of eutectic mixtures as reaction media, as an improvement in terms of selectivity and sustainability. This review aims to show the newly reported protocols in the field, subdivided by reaction class as a ‘toolbox’ guide for organic synthesis.
Giornate Italo-Francesi di Chimica, 2018
Angewandte Chemie, 2020
The selective formal insertion (homologation) of a carbon unit bridging the two trifluoroacetamid... more The selective formal insertion (homologation) of a carbon unit bridging the two trifluoroacetamidoyl chlorides (TFAICs) units is reported. The tactic is levered on a highly chemoselective homologation-metalation-acyl nucleophilic substitution sequence which precisely enables to assemble novel trifluoromethylated β-diketiminates within a single synthetic operation. Unlike previous homologations conducted with LiCH2Cl furnishing aziridines, herein we exploit the unique capability of iodomethyllithium to act contemporaneously as a C1 source (homologating effect) and metalating agent. The mechanistic rationale grounded on experimental evidences supports the hypothesized proposal and, the structural analysis gathers key aspects of this class of valuable ligands in catalysis.
Strigolactones - Biology and Applications, 2019
Focus of this chapter is the chemistry of Strigolactones. The structural features that identify t... more Focus of this chapter is the chemistry of Strigolactones. The structural features that identify the canonical versus non canonical Strigolactones, as well as the stereochemistry of the Strigol type and Orobanchol type families will be described. A special emphasis will be devoted to the total synthesis of natural Strigolactones as the most reliable and recommended method for successful structure elucidation of these natural products. However, due the complexity of the target molecules and to the high stereochemical control required to retain bioactivity, the synthesis of natural Strigolactones is currently not feasible on a multigram scale for applications in agriculture. In order to study the effect of Strigolactones on various biological processes, model compounds were designed and prepared. Synthetic Strigolactones can be classified into two main categories: (a) analogues, whose structure is very similar to natural SLs; (b) mimics, whose structure is much simpler, but showing a bioactivity resembling that of SLs. A survey of the most promising structures for agricultural applications and the synthetic pathways to access them is herein provided.
Materials, 2021
Deep Eutectic Systems (DESs) are obtained by combining Hydrogen Bond Acceptors (HBAs) and Hydroge... more Deep Eutectic Systems (DESs) are obtained by combining Hydrogen Bond Acceptors (HBAs) and Hydrogen Bond Donors (HBDs) in specific molar ratios. Since their first appearance in the literature in 2003, they have shown a wide range of applications, ranging from the selective extraction of biomass or metals to medicine, as well as from pollution control systems to catalytic active solvents and co-solvents. The very peculiar physical properties of DESs, such as the elevated density and viscosity, reduced conductivity, improved solvent ability and a peculiar optical behavior, can be exploited for engineering modular systems which cannot be obtained with other non-eutectic mixtures. In the present review, selected DESs research fields, as their use in materials synthesis, as solvents for volatile organic compounds, as ingredients in pharmaceutical formulations and as active solvents and cosolvents in organic synthesis, are reported and discussed in terms of application and future perspecti...
Current Medicinal Chemistry, 2017
Background: Fungi are a well-known and valuable source of compounds of therapeutic relevance, in ... more Background: Fungi are a well-known and valuable source of compounds of therapeutic relevance, in particular of novel anticancer compounds. Although seldom obtainable through isolation from the natural source, the total organic synthesis still remains one of the most efficient alternatives to resupply them. Furthermore, natural product total synthesis is a valuable tool not only for discovery of new complex biologically active compounds but also for the development of innovative methodologies in enantioselective organic synthesis. Methods: We undertook an in-depth literature searching by using chemical bibliographic databases (SciFinder, Reaxys) in order to have a comprehensive insight into the wide research field. The literature has been then screened, refining the obtained results by subject terms focused on both biological activity and innovative synthetic procedures. Results: The literature on fungal metabolites has been recently reviewed and these publications have been used as ...
Org. Biomol. Chem., 2017
Heck functionalization of azadipyrromethenes (aza-DIPY) allows the introduction of suitable funct... more Heck functionalization of azadipyrromethenes (aza-DIPY) allows the introduction of suitable functional groups to convert aza-BODIPY in bioconjugate complexes.
Organic & Biomolecular Chemistry, 2014
Fluorescent strigolactones have been designed and synthesized to fit bioimaging requirements.
Dyes and Pigments, 2021
A small library of 2,6-and 3,5-distyrenyl-substituted carborane-BODIPY dyes was efficiently synth... more A small library of 2,6-and 3,5-distyrenyl-substituted carborane-BODIPY dyes was efficiently synthesized by means of a Pd-catalyzed Heck coupling reaction. Styrenyl-carborane derivatives were exploited as molecular tools to insert two carborane clusters into the fluorophore core and to extend the π-conjugation of the final molecule in a single synthetic step. The synthetic approach allows to increase the molecular diversity of this class of fluorescent dyes by the synthesis of symmetric or asymmetric units with enhanced boron content. The structural characterization and photoluminescence (PL) properties of synthesized dyes were evaluated. The developed compounds exhibit a significant bathochromic shift compared to their parent fluorophore scaffolds, and absorption and emission patterns were practically unaffected by the different substituents (Me or Ph) on the Ccluster atom (Cc) of the carborane cage or the cluster isomer (ortho-or metacarborane). Remarkably, the presence of carborane units at 2,6-positions of the fluorophore produced a significant increase of the emission fluorescent quantum yields, which could be slightly tuned by changing the Cc-substituent and the carborane isomer, as well as introducing ethylene glycol groups at the meso-position of 2 the BODIPY. All these features make these dyes promising candidates for further investigations in live-cell imaging and bio-supramolecular assays.
Alkoxydienyl boronates 1a and 1b and alkoxystyryl boronate 2 have been used in various copper med... more Alkoxydienyl boronates 1a and 1b and alkoxystyryl boronate 2 have been used in various copper mediated cross-coupling reactions with azoles. A variety of N-alkoxydienyl-and Nstyrylazoles have been synthesized under mild conditions.
Molecules
Strigolactones (SLs) are a class of sesquiterpenoid plant hormones that play a role in the respon... more Strigolactones (SLs) are a class of sesquiterpenoid plant hormones that play a role in the response of plants to various biotic and abiotic stresses. When released into the rhizosphere, they are perceived by both beneficial symbiotic mycorrhizal fungi and parasitic plants. Due to their multiple roles, SLs are potentially interesting agricultural targets. Indeed, the use of SLs as agrochemicals can favor sustainable agriculture via multiple mechanisms, including shaping root architecture, promoting ideal branching, stimulating nutrient assimilation, controlling parasitic weeds, mitigating drought and enhancing mycorrhization. Moreover, over the last few years, a number of studies have shed light onto the effects exerted by SLs on human cells and on their possible applications in medicine. For example, SLs have been demonstrated to play a key role in the control of pathways related to apoptosis and inflammation. The elucidation of the molecular mechanisms behind their action has inspi...
Chemistry – A European Journal
Antibiotics
The selective synthesis of active pharmaceutical molecules is a challenging issue, particularly w... more The selective synthesis of active pharmaceutical molecules is a challenging issue, particularly when attempting to make the reactions even more sustainable. The present work focuses on the microwave-assisted hydrogenolysis of oxytetracycline to selectively produce α-doxycycline. Although the combination of microwave irradiation and a heterogeneous rhodium catalyst provided good conversions, the selective synthesis of active α-doxycycline was only achieved when an oxytetracycline-cyclodextrin complex was used as the starting material, giving the desired product at 34.0% yield in a one-step reaction under very mild conditions.
The Journal of Organic Chemistry
The reactivity of "furan-ynes" in combination with pyridine and quinoline N-oxides in the presenc... more The reactivity of "furan-ynes" in combination with pyridine and quinoline N-oxides in the presence of a Au(I) catalyst, has been studied, enabling the synthesis of three different heterocyclic scaffolds. Selective access to two out of the three possible products, a dihydropyridinone and a furan enone, has been achieved through the fine-tuning of the reaction conditions. The reactions proceed smoothly at room temperature and open-air, and were further extended to a broad substrate scope, thus affording functionalized dihydropyridinones and pyranones.
European Journal of Organic Chemistry
Molecules
The unprecedented Nazarov cyclization of a model divinyl ketone using phosphonium-based Deep Eute... more The unprecedented Nazarov cyclization of a model divinyl ketone using phosphonium-based Deep Eutectic Solvents as sustainable non-innocent reaction media is described. A two-level full factorial Design of Experiments was conducted for elucidating the effect of the components of the eutectic mixture and optimizing the reaction conditions in terms of temperature, time, and substrate concentration. In the presence of the Deep Eutectic Solvent (DES) triphenylmethylphosphonium bromide/ethylene glycol, it was possible to convert more than 80% of the 2,4-dimethyl-1,5-diphenylpenta-1,4-dien-3-one, with a specific conversion, into the cyclopentenone Nazarov derivative of 62% (16 h, 60 °C). For the reactions conducted in the DES triphenylmethylphosphonium bromide/acetic acid, quantitative conversions were obtained with percentages of the Nazarov product above 95% even at 25 °C. Surface Responding Analysis of the optimized data furnished a useful tool to determine the best operating conditions...
Processes
The employment of used vegetable oils (UVOs) as raw materials in key sectors as energy production... more The employment of used vegetable oils (UVOs) as raw materials in key sectors as energy production or bio-lubricant synthesis represents one of the most relevant priorities in the European Union (EU) normative context. In many countries, the development of new production processes based on the circular economy model, as well as the definition of future energy and production targets, involve the utilization of wastes as raw material. In this context, the main currently applied EU regulations are presented and discussed. As in the EU, the general legislative process consists of the definition in each State Member of specific legislation, which transposes the EU indications. Two relevant countries are herein considered: Italy and Spain. Through the analysis of the conditions required in both countries for UVOs’ collection, disposal, storage, and recycling, a wide panorama of the current situation is provided.
Current Genetics, 2016
Strigolactones (SLs) as components of root exudates induce hyphal branching of arbuscular mycorrh... more Strigolactones (SLs) as components of root exudates induce hyphal branching of arbuscular mycorrhizal (AM) fungi which is thought to favor the establishment of the beneficial symbiosis. Little is known on how AM fungi respond to SLs. Since AM fungi are poor model systems due to their obligate biotrophism and the lack of genetic transformation protocols, we took advantage of the sensitivity of several phytopathogenic fungi to GR24, a synthetic SLs analog. With the aim to identify the molecular determinants involved in SLs response in AM fungi and assuming conserved mechanisms in the fungal kingdom, we exploited the fungal pathogens Botrytis cinerea and Cryphonectria parasitica, for which mutant collections are available. Exposure of B. cinerea and C. parasitica to GR24 embedded in solid medium led to reduction of fungal radial growth. We set up the screening of a set of well characterized gene deletion mutants to isolate genotypes with altered responses to SLs. Two B. cinerea mutants (defective of BcTrr1, a thioredoxin reductase and BcLTF1, a GATA transcription factor) turned out to be less responsive to GR24. One feature shared by the two mutants is the overproduction of reactive oxygen species (ROS). Indeed, an oxidizing effect was observed in a B. cinerea strain expressing a redox-sensitive GFP2 in the mitochondrial intermembrane space upon exposure to GR24. ROS and mitochondria are therefore emerging as mediators of SLs actions.
Molecules
During the last decade, a wide spectrum of applications and advantages in the use of deep eutecti... more During the last decade, a wide spectrum of applications and advantages in the use of deep eutectic solvents for promoting organic reactions has been well established among the scientific community. Among these synthetic methodologies, in recent years, various examples of biocatalyzed processes have been reported, making use of eutectic mixtures as reaction media, as an improvement in terms of selectivity and sustainability. This review aims to show the newly reported protocols in the field, subdivided by reaction class as a ‘toolbox’ guide for organic synthesis.
Giornate Italo-Francesi di Chimica, 2018
Angewandte Chemie, 2020
The selective formal insertion (homologation) of a carbon unit bridging the two trifluoroacetamid... more The selective formal insertion (homologation) of a carbon unit bridging the two trifluoroacetamidoyl chlorides (TFAICs) units is reported. The tactic is levered on a highly chemoselective homologation-metalation-acyl nucleophilic substitution sequence which precisely enables to assemble novel trifluoromethylated β-diketiminates within a single synthetic operation. Unlike previous homologations conducted with LiCH2Cl furnishing aziridines, herein we exploit the unique capability of iodomethyllithium to act contemporaneously as a C1 source (homologating effect) and metalating agent. The mechanistic rationale grounded on experimental evidences supports the hypothesized proposal and, the structural analysis gathers key aspects of this class of valuable ligands in catalysis.
Strigolactones - Biology and Applications, 2019
Focus of this chapter is the chemistry of Strigolactones. The structural features that identify t... more Focus of this chapter is the chemistry of Strigolactones. The structural features that identify the canonical versus non canonical Strigolactones, as well as the stereochemistry of the Strigol type and Orobanchol type families will be described. A special emphasis will be devoted to the total synthesis of natural Strigolactones as the most reliable and recommended method for successful structure elucidation of these natural products. However, due the complexity of the target molecules and to the high stereochemical control required to retain bioactivity, the synthesis of natural Strigolactones is currently not feasible on a multigram scale for applications in agriculture. In order to study the effect of Strigolactones on various biological processes, model compounds were designed and prepared. Synthetic Strigolactones can be classified into two main categories: (a) analogues, whose structure is very similar to natural SLs; (b) mimics, whose structure is much simpler, but showing a bioactivity resembling that of SLs. A survey of the most promising structures for agricultural applications and the synthetic pathways to access them is herein provided.
Materials, 2021
Deep Eutectic Systems (DESs) are obtained by combining Hydrogen Bond Acceptors (HBAs) and Hydroge... more Deep Eutectic Systems (DESs) are obtained by combining Hydrogen Bond Acceptors (HBAs) and Hydrogen Bond Donors (HBDs) in specific molar ratios. Since their first appearance in the literature in 2003, they have shown a wide range of applications, ranging from the selective extraction of biomass or metals to medicine, as well as from pollution control systems to catalytic active solvents and co-solvents. The very peculiar physical properties of DESs, such as the elevated density and viscosity, reduced conductivity, improved solvent ability and a peculiar optical behavior, can be exploited for engineering modular systems which cannot be obtained with other non-eutectic mixtures. In the present review, selected DESs research fields, as their use in materials synthesis, as solvents for volatile organic compounds, as ingredients in pharmaceutical formulations and as active solvents and cosolvents in organic synthesis, are reported and discussed in terms of application and future perspecti...
Current Medicinal Chemistry, 2017
Background: Fungi are a well-known and valuable source of compounds of therapeutic relevance, in ... more Background: Fungi are a well-known and valuable source of compounds of therapeutic relevance, in particular of novel anticancer compounds. Although seldom obtainable through isolation from the natural source, the total organic synthesis still remains one of the most efficient alternatives to resupply them. Furthermore, natural product total synthesis is a valuable tool not only for discovery of new complex biologically active compounds but also for the development of innovative methodologies in enantioselective organic synthesis. Methods: We undertook an in-depth literature searching by using chemical bibliographic databases (SciFinder, Reaxys) in order to have a comprehensive insight into the wide research field. The literature has been then screened, refining the obtained results by subject terms focused on both biological activity and innovative synthetic procedures. Results: The literature on fungal metabolites has been recently reviewed and these publications have been used as ...
Org. Biomol. Chem., 2017
Heck functionalization of azadipyrromethenes (aza-DIPY) allows the introduction of suitable funct... more Heck functionalization of azadipyrromethenes (aza-DIPY) allows the introduction of suitable functional groups to convert aza-BODIPY in bioconjugate complexes.
Organic & Biomolecular Chemistry, 2014
Fluorescent strigolactones have been designed and synthesized to fit bioimaging requirements.
Dyes and Pigments, 2021
A small library of 2,6-and 3,5-distyrenyl-substituted carborane-BODIPY dyes was efficiently synth... more A small library of 2,6-and 3,5-distyrenyl-substituted carborane-BODIPY dyes was efficiently synthesized by means of a Pd-catalyzed Heck coupling reaction. Styrenyl-carborane derivatives were exploited as molecular tools to insert two carborane clusters into the fluorophore core and to extend the π-conjugation of the final molecule in a single synthetic step. The synthetic approach allows to increase the molecular diversity of this class of fluorescent dyes by the synthesis of symmetric or asymmetric units with enhanced boron content. The structural characterization and photoluminescence (PL) properties of synthesized dyes were evaluated. The developed compounds exhibit a significant bathochromic shift compared to their parent fluorophore scaffolds, and absorption and emission patterns were practically unaffected by the different substituents (Me or Ph) on the Ccluster atom (Cc) of the carborane cage or the cluster isomer (ortho-or metacarborane). Remarkably, the presence of carborane units at 2,6-positions of the fluorophore produced a significant increase of the emission fluorescent quantum yields, which could be slightly tuned by changing the Cc-substituent and the carborane isomer, as well as introducing ethylene glycol groups at the meso-position of 2 the BODIPY. All these features make these dyes promising candidates for further investigations in live-cell imaging and bio-supramolecular assays.
Alkoxydienyl boronates 1a and 1b and alkoxystyryl boronate 2 have been used in various copper med... more Alkoxydienyl boronates 1a and 1b and alkoxystyryl boronate 2 have been used in various copper mediated cross-coupling reactions with azoles. A variety of N-alkoxydienyl-and Nstyrylazoles have been synthesized under mild conditions.
Molecules
Strigolactones (SLs) are a class of sesquiterpenoid plant hormones that play a role in the respon... more Strigolactones (SLs) are a class of sesquiterpenoid plant hormones that play a role in the response of plants to various biotic and abiotic stresses. When released into the rhizosphere, they are perceived by both beneficial symbiotic mycorrhizal fungi and parasitic plants. Due to their multiple roles, SLs are potentially interesting agricultural targets. Indeed, the use of SLs as agrochemicals can favor sustainable agriculture via multiple mechanisms, including shaping root architecture, promoting ideal branching, stimulating nutrient assimilation, controlling parasitic weeds, mitigating drought and enhancing mycorrhization. Moreover, over the last few years, a number of studies have shed light onto the effects exerted by SLs on human cells and on their possible applications in medicine. For example, SLs have been demonstrated to play a key role in the control of pathways related to apoptosis and inflammation. The elucidation of the molecular mechanisms behind their action has inspi...
Chemistry – A European Journal
Antibiotics
The selective synthesis of active pharmaceutical molecules is a challenging issue, particularly w... more The selective synthesis of active pharmaceutical molecules is a challenging issue, particularly when attempting to make the reactions even more sustainable. The present work focuses on the microwave-assisted hydrogenolysis of oxytetracycline to selectively produce α-doxycycline. Although the combination of microwave irradiation and a heterogeneous rhodium catalyst provided good conversions, the selective synthesis of active α-doxycycline was only achieved when an oxytetracycline-cyclodextrin complex was used as the starting material, giving the desired product at 34.0% yield in a one-step reaction under very mild conditions.
The Journal of Organic Chemistry
The reactivity of "furan-ynes" in combination with pyridine and quinoline N-oxides in the presenc... more The reactivity of "furan-ynes" in combination with pyridine and quinoline N-oxides in the presence of a Au(I) catalyst, has been studied, enabling the synthesis of three different heterocyclic scaffolds. Selective access to two out of the three possible products, a dihydropyridinone and a furan enone, has been achieved through the fine-tuning of the reaction conditions. The reactions proceed smoothly at room temperature and open-air, and were further extended to a broad substrate scope, thus affording functionalized dihydropyridinones and pyranones.
European Journal of Organic Chemistry
Molecules
The unprecedented Nazarov cyclization of a model divinyl ketone using phosphonium-based Deep Eute... more The unprecedented Nazarov cyclization of a model divinyl ketone using phosphonium-based Deep Eutectic Solvents as sustainable non-innocent reaction media is described. A two-level full factorial Design of Experiments was conducted for elucidating the effect of the components of the eutectic mixture and optimizing the reaction conditions in terms of temperature, time, and substrate concentration. In the presence of the Deep Eutectic Solvent (DES) triphenylmethylphosphonium bromide/ethylene glycol, it was possible to convert more than 80% of the 2,4-dimethyl-1,5-diphenylpenta-1,4-dien-3-one, with a specific conversion, into the cyclopentenone Nazarov derivative of 62% (16 h, 60 °C). For the reactions conducted in the DES triphenylmethylphosphonium bromide/acetic acid, quantitative conversions were obtained with percentages of the Nazarov product above 95% even at 25 °C. Surface Responding Analysis of the optimized data furnished a useful tool to determine the best operating conditions...
Processes
The employment of used vegetable oils (UVOs) as raw materials in key sectors as energy production... more The employment of used vegetable oils (UVOs) as raw materials in key sectors as energy production or bio-lubricant synthesis represents one of the most relevant priorities in the European Union (EU) normative context. In many countries, the development of new production processes based on the circular economy model, as well as the definition of future energy and production targets, involve the utilization of wastes as raw material. In this context, the main currently applied EU regulations are presented and discussed. As in the EU, the general legislative process consists of the definition in each State Member of specific legislation, which transposes the EU indications. Two relevant countries are herein considered: Italy and Spain. Through the analysis of the conditions required in both countries for UVOs’ collection, disposal, storage, and recycling, a wide panorama of the current situation is provided.